I created a mnemonics and it is hashed using pbdkf2
function to get a root seed. So this root seed should be hashed again with HMAC-SHA512 to get the master key (Master private key and chain code). So for a HMAC-SAH512 we need a key and data, so in this case what should be the key? Data should be the root seed and what should I give as key in hmac function.
I gave "Bitcoin Seed" as key and generated a hash, but it is not matching the output showed on Ian Coleman's bip39 website.